Fuel-injection adjusting device



June 26, 1962 H. o. SCHERENBERG ETAL 3,040,723

FUEL-INJECTION ADJUSTING DEVICE.

Filed March 11, 1960 A 6 6:2 26 ,1 7 F== E a a INVENTORS I HANS o. SCHERENBERG 3 |4 JOHANNES GASSMANN ATTORNEY atent 3,040,723 Patented June 26, 1962 Daimier-Benz Aktiengesellschaft, Stuttgart-Unterturlrheim, Germany Filed Mar. 11, 1960, Ser. No. 14,317 Claims priority, application Germany Mar. 19, 1959 4 Claims. (Cl. 123-139) The present invention relates to an adjusting installation for adjusting the time of the point of injection for injection pumps provided with a drive means in the form of a camshaft and a tappet for internal combustion engines.

The present invention aims at a structural simplification of an adjusting installation for adjusting the time of the injection point of the type mentioned hereinabove and to render the same less expensive as well as to increase the reliability of operation thereof.

The present invention is particularly intended for engine constructions in which the camshaft and the engine control shaft form an integral part.

The present invention essentially consists in arranging the tappet guide means so as to he movable, preferably, rectangularly in relation to the camshaft. In connection therewith, provision may be made so as to render the tappet movable and adjustable essentially rectangularly with respect to the camshaft axes by means of a toothed rack of a worm drive or the like within a predetermined range into any desired positions.

The following structural basic concepts for the construction of the tappet guide arrangement in accordance with the present invention have proved themselves as particularly appropriate:

On the one hand, the tappet guidance may be arranged within an eccentric bushing which is adapted to be rotated, preferably over a gear rim and toothed rack connection. On the other hand, the entire tappet guide arrangement may be adapted to be pivoted preferably about an axis disposed essentially parallel to the camshaft axis.

In order to attain, with a pivotal tappet guide means, a loading of the upper tappet end which is as satisfactory and unobjectionable as possible, and in order to attain a simple bearing support of the structural parts constituting effectively the pivot axis, the pivot axis in accordance with the present invention is advantageously located at the upper end or within the region of the upper end of the tappet.

For purposes of transmitting the control magnitude to the lower parts of the tappet which are operatively connected with the cam, the pivotal movement may take place in an advantageous manner by means of an arm pref erably forming simultaneously the bushing guide means which is acted upon by a rotatable eccentric, cam or the like and by a lever operatively connected therewith.

Accordingly, it is an object of the present invention to provide an adjusting mechanism for selectively adjusting the timing point of injection for a fuel injection system, especially for internal combustion engines, which obviates the disadvantages of the prior art devices.

It is another object of the present invention to provide an adjusting mechanism for adjusting the timing of the injection point of an injection pump provided with a cam shaft drive means and a tappet which considerably reduces the number of parts necessary in the device, is simpler in construction as well as less expensive in manufacture and assembly.

Still another object of the present invention resides in the provision of an adjusting mechanism of the type described hereinabove for selectively adjusting the timing of the injection point which increases the operational reliability thereof.

Another object of the present invention is the provision of an adjusting mechanism for adjusting the timing of the injection point of a fuel injection pump which is provided with a cam-driven tappet or plunger in which the forces and stresses particularly in the tappet end and the part operatively connected therewith are advantageously distributed to avoid any peak stresses.

These and other objects, features and advantages of the present invention will become more obvious from the following description when taken in connection. with the accompanying drawing which shows, for purposes of illustration only, two embodiments in accordance with the present invention and wherein:

FIGURE 1 is a cross-sectional view through a first embodiment of an adjusting mechanism in accordance with the present invention and, more particularly, through the tappet guide means thereof provided with an eccentric bushing, and

FIGURE 2 is a cross-sectional view through a modified embodiment of an adjusting mechanism in accordance with the present invention provided with a tappet guide means having a pivotal arm.

Referring now to the drawing, wherein like reference numerals are used throughout the two views to designate like parts, FIGURES 1 and 2 illustrate a tappet drive arrangement which consists of a cam 1 and of a .roller member 2 normally riding along the cam surface of cam 1. As the cam 1 rotates in the direction of arrow 3, the roller member 2 follows along the surface 4 of cam 1, as is well known.

The roller member 2 is arranged at the lower end of the tappet 5 which is adapted to reciprocate in the upward and downward directions corresponding to the double arrow 6,;and more particularly, which is adapted to carry out such reciprocatory movements with the aid of or in opposition to the force exerted thereon by the coil spring 7. The coil spring 7 is disposed within a bushing 8 rigidly connected with the support of the roller member 2 which support may be of any known suitable construction.

The bushing 8 is adapted to slide within a relatively stationary bushing 9 in the embodiment of FIGURE 1 which bushing 9, in turn, is surrounded by an eccentric bushing 10. The eccentric bushing 10 is rotatably supported within the housing block 11. The rotation of the eccentric bushing 14} takes place over the gear-rimtoothed-rack connection consisting of the gear rim 12 provided at the upper end of the eccentric bushing 10 and of the toothed rack 13 suitably supported within the housing 11. The linear movements of the toothed rack 13 take place thereby essentially in a direction perpendicular to the plane of the drawing of FIGURE 1.

Operation The adjusting operation of the timing of the injection point takes place in the embodiment of FIGURE 1 as follows:

The control magnitude is transmitted by means of the toothed rack 13 by displacing the same in the longitudinal direction thereof. Since the toothed rack 13' is in meshing engagement with the gear rim 12, a rotation of the eccentric bushing 10 is caused by linear displacement of the toothed rack 13. With a rotation of the eccentric bushing 10, the center axis of the eccentric bore of the bushing 10 moves from the initial position thereof into a position displaced with respect to the axis 14 of the cam shaft. The bushing y together with the inner parts thereof and therewith also the tappet 5 itself thereby move toward the right or left, as viewed in FIGURE 1, upon movement of 3 r. the eccentric bore in bushing 16 caused by rotation. thereof.

The displacement components of the tappet 5 perpendicularly to the axis 14 of the cam shaft is indicated in FIG- URE 1, for example, by the distantce 15.

If the axis17 of the roller member 2 is disposed exactly vertically above the axis 14 of the cam shaft, then the tappet 5 assumes the highest position thereof, i.e. its upper dead-center position when the highest point or peak 16 of thecam 1 is also disposed exactly vertically above the axis 14. If now the tappet, 5 is displaced toward the left by an amount or dimensions 15 (FIGURE 1) by rotation of the eccentric bushing 18, then the upper dead-center position thereof, if the direction of rotation of the cam 1 is assumed to be in the direction of arrow 3, is advanced. Of course, the time period of advance is dependent on the rotation of the eccentric bushing 10. By thus advancing the top dead-center position of the tappet 5, an earlier injection of the fuel is achieved. i

i In the embodhnent according to FIGURE 2, the same conditions exist with respect'to thedrive elements for the tappet 5' as exist inco'nnection with the embodiment of FIGURE 1. As in the embodiment of FIGURE 1, the

roller member 2 of the embodiment of FiGURE 2 also runs alongthe surface 4 of the cam 11.

In the normal or center position, the tappet .5 is in the upper dead-center position thereof when the highest point or peak 16 of the cam llis disposed vertically above the axis 14 of the cam shaft.

A'displacement of the roller member 2 from the normal or center position thereof is obtained, in FIGURE 2, by pivotal movement of the entire tappet guide means about the point '18. Point 18 thereby represents the effective pivot axis, indicated in FIGURE 2 by a small circle. The entirety of the tappet guide means consists of an arm 20 andof a bushing 19 which is provided on the inside thereof with the cylindrically-shaped sliding'sur'face for the guide bushing 8 of the tappet 5. The bushing 19 is inserted into the housing 11 with plentiful play.

The'totality of parts constituting the tappet and tappet guide means is pivoted about the pivot axis 18 by an eccentric 121 corresponding to the double arrows 22 and 23. The eccentric 21 itself is providedwith a lever 24 which is adapted to be moved corresponding to the double arrow 25 and therewith leads by adjustment thereof to the rotation of the parts '19 and 29 which are integral with each other. In order to assure continuous abutment of the arm 20 against the eccentric '21, the arm 20 is springloaded' on the side thereof opposite the side of eccentric 21byaspring26. i j

- The displacements of the axis 17 of the roller member 2 corresponding to the double arrow 23 lead to an advancing or retarding ofthe time point of the injection, for the reasons already mentioned and explainedf'in connection with the embodiment of FIGURE 1 in which the tappet 5 assumes the upper dead-center position thereof and therewith eifects the injection of the fuel. l

in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of 'many changes and modifications within the spirit and scope of the present invention.

For example, the possibility of moving the tappet guide means which constitutes the principal basic concept of the present invention may also be applied to any other suitable manner of construction different from that shown in connection with the embodiments of FIGURES 1 and 2. For

, cam shaft axis Within a predetermined range.

we, therefore, do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

' We claim:

1. An adjusting mechanism for adjusting the time of the injection point for injection pumps comprising tappet means, cam means for driving said tappet means, and guide means for adjnsta-bly guiding said tappet means within said mechanism to move said tappet means essentially perpendicularly to the axis of said cam means, said guide means including an eccentric bushing rotatably supported within said mechanism, whereby said tappet guide means is laterally adjusted by rotation of said eccentric bushing.

2. An adjusting mechanism according to claim 1, further comprising worm gear drive means operativeiy connected with said guide means for adjustably moving said tappet means essentially perpendicularly to said axis within a predetermined range into any desired positions.

3. Anadjusting mechanism according to claim 1, further comprising a toothed rack and gear means at said eccentric bushing in meshing engagement with said toothed rack to thereby rotate said bushing by linear displacement of said rack.

4. An adjusting mechanism for adjusting the time of the injection point for injection pumps used with internal combustion engines, comprising a relatively stationary part, an eccentric bushing rotatably supported within said eccentric part, a relatively fixed bushing within said eccentric bushingptappet means including a bearing bushing slidingly received within said'relatively fixed bushing, cam means, a roller member in operative engagement with said cam means, support means secured to said bearing bushing 1 adjust the injection point of the injection pump.

The pivotal movements of the axis 17 of the roller memher 2 corresponding to the double arrow 23, therefore, have the same control effects as the essentially horizontal displacements of the tappet guide means according to the embodiment of FIGURE '1, the magnitude of which was i 'While we have shown and described two'embodiments Franks Sept. 1 1936 Scott 'Nov. 7, 1939 

